Outboard motor propeller construction



United States Patent 3,102,506 OUTBOARD MOTOR PROPELLER CONSTRUCTIONElmer C. Kiekhaeler, Winter Haven, Fla., assignor, by

mesne assignments, to Kiekhaefer Corporation, Chlcago, 11]., acorporation of Delaware Continuation of application Ser. No. 47,817,Aug. 5, 1960. This application Feb. 27, 1962, Ser. No. 177,697 Claims.(Cl. 11S17) This invention relates to reversible outboard motors of thetype wherein the exhaust gases are expelled through the propeller huband provides for improved flow of exhaust gases through the propellerhub when the motor is operated in reverse.

In outboard motors which exhaust the products of engine combustionthrough the propeller hub, the hub generally includes a tubular innerhub member adapted for securcment on the propeller shaft of the motorand a tubular outer hub member which carries the propeller blades. Theinner and outer hub members are spaced apart by means of a plurality ofstruts to form an exhaust passage therebetween which conducts theproducts of combustion from the exhaust passage within the drive shafthousing of the motor for discharge into the water re arwardly of thepropeller.

When operating a motor having a propeller hub exhaust system in reverseas when backing up to boat to which the motor is secured, a considerablevolume of water enters the propeller hub exhaust outlet and interfereswith the normal flow of exhaust gases from the engine. As a result backpressures may develop in the exhaust system which adversely affect theefficiency of the engine. It is generally an object of this invention topush or pump the water from the interior of the propeller hub when themotor is operated in reverse and thereby assist the flow of exhaustgases from the engine.

According to the invention, the struts joining the inner and outer hubmembers of a propeller for a reversible outboard motor having apropeller hub exhaust system :are disposed angularly with respect to theaxis of the hub members so as to form a pump impeller adapted to push orpump the Water from the hub and thereby assist the flow of exhaust gaseswhen the motor is operated in reverse.

The drawings furnished herewith illustrate the best mode of carrying outthe invention as presently contemplated and set forth hereinafter.

In the drawings:

FIGURE 1 is a side elevation of an outboard motor having a reversibleengine and which is adapted to move a boat selectively in forward andreverse directions;

FIGURE 2 is an enlarged partial sectional view of an outboard motor andshows the propeller hub exhaust system of this invention;

FIGURE 3 is an enlarged view of the propeller hub with parts broken awayand sectioned to show one of the struts adapted to push or pump waterfrom the hub when the motor is operated in reverse; and

FIGURE 4 is an end view of the propeller hub of this invention.

Referring to the drawings, the outboard motor includes a reversibleengine, not shown, adapted to propel the motor in both forward andrearward directions and disposed within the powerhcad 1 supported at theupper end of the drive shaft housing 2 and a lower underwater unit 3carried at the lower end of the drive shaft housing. The drive shaft 4extends downwardly within housing 2 and drivingly connects the enginewith the propeller shaft 5 of the lower unit 3 through bevel gears 6 and7 carried respectively by the drive shaft and propeller shaft.

3,102,506 Patented Sept. 3, 1963 "ice The lower unit 3 includes ahousing 8 providing a downwardly extending passage 9 within which thedrive shaft 4 is rotatably mounted and a lower horizontal chamber 10into which the lower end of the drive shaft extends. An exhaust passage11 communicating with the engine surrounds housing 8 and connects withchamber 10 rearwardly of the drive shaft.

A portion of chamber 10 rearwardly of the drive shaft constitutes acylindrical bore 12 and is adapted to receive the spool-like member 13within which the propeller shaft 5 is rotatably supported. The enlargedforward portion 14 of member 13 engages the wall of bore 12 and servesto isolate the forward portion of chamber 10 containing gears 6 and 7from the remainder of chamber 10 which communicates with the exhaustpassage 11 of lower unit 3. Rearwardly the spool-like member 13 isprovided with an annular flange 15 which engages the wall of bore 12adjacent to the threaded opening 16 to the bore roarwardly of unit 3. Anexternally threaded annular collar 17 is threaded into the bore opening16 and engages the flange 15 to secure the member 13 within the bore 12.The flange 15 of member 13 is provided with a plurality ofcircumferentially spaced openings 18 through which the exhaust gasespass from the passage 11 to the propeller unit 19.

The propeller unit 19 comprises an annular outer hub sleeve 29 whichoverlaps the rearwardly extending portion of collar 17 and carries thepropeller blades 21. The hub sleeve 2! is spaced outwardly from theinner hub sleeve 22 and a plurality of struts 23 extend between andinterconnect the sleeves. The bore 24 of hub sleeve 22 is adapted to bereceived on the rearwardly extending splined portion of propeller shaft5 and is secured between shoulder 25 and the nut 26 threaded onto theend of shaft 5. In operation, the exhaust gases entering the propellerunit 19 pass between the spaced sleeves 20 and 22 for discharge throughthe nozzle opening 27 rearwardly of the unit.

When operating the outboard motor in reverse, a considerable volume ofwater ordinarily enters the propeller unit 10 and fills to aconsiderable depth the exhaust passages in the underwater unit 3 anddrive shaft housing 2 which interferes with the normal llow of exhaustgases from the engine giving rise to back pressures in the exhaustsystem resulting in a lesser engine efficiency.

According to this invention, the struts 23 interconnecting the hubsleeves 2G and 22 are provided with an angularity relative to the axisof the hub sleeve such that the [forward edges 28 of the struts lead thecorresponding rearward edges 29 rotatively when the propeller rotates toprovide for reverse operation of the propulsion unit to form a simpleimpeller capable of pumping or pushing Water from the interior of thepropeller unit 19 during reverse operation. In the case of an outboardpropulsion unit wherein the propeller blades 21 have a fixed angularity,the struts 23 have an angularity generally opposed to that of thepropeller blades. The pumping action of the struts 23 during reverseoperation of the motor substantially prevents the entry of water intothe exhaust passages of the underwater unit 3 and the drive shafthousing 2 to materially assist the flow of exhaust gases from theengine.

During forward operation of the motor, the hub is substantially free ofwater so that the struts 23 remain ineffectual as pump impellers andutter negligible resistance to the flow of exhaust gases through thepropeller unit 19.

This application is a continuation of applicant's copending applicationSerial No. 47,817, filed August 5, i960, and entitled Outboard MotorPropeller Construction, now abandoned.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. In a propulsion unit for a boat; a propeller; means to rotate thepropeller selectively in one direction for forward operation of thepropulsion unit and in the opposite direction for reverse operation ofthe unit; said propeller comprising an outer hub sleeve and an inner hubsleeve, said sleeves being radially spaced to provide a hub passagetherebetween for conducting exhaust gases rear- Wardly from the unit,and a plurality of struts in said passage extending between andconnecting said sleeves, said struts being angularly disposed relativeto the axis of said sleeves and having the forward edges thereof leadthe corresponding rearward edges rotatively when the propeller rotatesin said opposite direction whereby to form an impeller within the hubpassage adapted to push water from the interior thereof during reverseoperation of the unit.

2. In a propulsion unit for a boat; a propeller mounted on a generallyhorizontal shaft; means to rotate the propeller in opposed directionsselectively to provide for forward and reverse operation of the unit;said propeller comprising an outer sleeve member, a plurality ofpropeller blades carried by the outer sleeve member and disposedangularly with respect to the axis of said sleeve member, an innersleeve member adapted to be secured on the generally horizontalpropeller shaft, said sleeve members being radially spaced to provide apassage therebetween for conducting exhaust gases rearwardly from theunit, and a plurality of struts extending between and connecting saidsleeve members, said struts being disposed angularly relative to theaxis of said sleeve members and opposite to the angularity of thepropeller blades to thereby form an impeller within the exhaust passageadapted to push Water from the interior of the propeller when thepropeller rotates to provide for reverse operation of the propulsionunit.

3. In an outboard motor; a propeller unit; an internalcombustion engineto drive said propeller unit; a housing member carrying said engine atthe upper end thereof and said propeller unit at the lower end thereof,said housing member having a passage adapted to conduct exhaust gasesfrom said engine to the propeller unit; said propeller unit beingselectively rotatable in one direction for forward operation of theoutboard motor and in the opposite direction for reverse operation ofthe motor and comprising an outer sleeve member and an inner sleevemember, said sleeve members being spaced apart radially to provide apassage therebetween to receive the exhaust gases from said housingmember and conduct same rearwardly through the unit, and a plurality ofstruts extending between and connecting said sleeves, said struts beingangularly disposed relative to the axis of said sleeve members andhaving the forward edges thereof lead the corresponding rearward edgesrotatively when the propeller rotates in said opposite direction wherebyto form an impeller within the exhaust passage of the propeller unitadapted to push water from the interior of the unit during reverseoperation of the outboard motor.

4. In a propeller for a watercraft propulsion unit, said propeller beingselectively rotatable in one direction for forward operation of thepropulsion unit and in the opposite direction for reverse operation ofthe unit and comprising an outer hub sleeve and an inner hub sleeve,said sleeves being radially spaced to provide a hub passage therebetweenfor conducting exhaust gases rearwardly from the unit, and a pluralityof struts in said passage extending between and connecting said sleeves,said struts being angularly disposed relative to the axis of saidsleeves and having the forward edges thereof lead the correspondingrearward edges rotatively when the propeller rotates in said oppositedirection whereby to form an impeller within the hub passage adapted topush water from the interior thereof during reverse operation of thepropulsion unit.

5. A propeller for underwater propulsion, comprising an outer hub sleeveand an inner hub sleeve spaced radially from each other to provide a hubpassage therebetween for discharging gases rearwardly from thepropeller, propeller blades extending outwardly from said outer hubsleeve and angularly disposed to provide forward and rearward propulsionby the propeller dependent upon the selective direction of rotationthereof, and a plurality of struts extending between and connecting saidsleeve members, said struts being disposed angularly relative to theaxis of said sleeve members and opposite to the angularity of thepropeller blades to thereby form an impeller within the exhaust passageadapted to push water from the interior of the propeller when thepropeller rotates to provide for reverse operation of the propulsionunit.

References Cited in the file of this patent UNITED STATES PATENTS1,941,360 Mathias Dec. 12, 1933 2,213,609 Ronning Sept. 3, 19402,948,354 Witt Aug. 9, 1960 FOREIGN PATENTS 376,647 Great Britain July14, 1932

1. IN A PROPULSION UNIT FOR A BOAT; A PROPELLER; MEANS TO ROTATE THEPROPELLER SELECTIVELY IN ONE DIRECTION FOR FORWARD OPERATION OF THEPROPULSION UNIT AND IN THE OPPOSITE DIRECTION FOR REVERSE OPERATION OFTHE UNIT; SAID PROPELLER COMPRISING AN OUTER HUB SLEEVE AND AN INNER HUBSLEEVE, SAID SLEEVES BEING RADIALLY SPACED TO PROVIDE A HUB PASSAGETHEREBETWEEN FOR CONDUCTING EXHAUST GASES REARWARDLY FROM THE UNIT, ANDA PLURALITY OF STRUTS IN SAID PASSAGE EXTENDING BETWEEN AND CONNECTINGSAID SLEEVES, SAID STRUTS BEING ANGULARLY DISPOSED RELATIVE TO THE AXISOF SAID SLEEVES AND HAVING THE FORWARD EDGES THEREOF LEAD THECORRESPONDING REARWARD EDGES ROTATIVELY WHEN THE PROPELLER ROTATES INSAID OPPOSITE DIRECTION WHEREBY TO FORM AN IMPELLER WITHIN THE HUBPASSAGE ADAPTED TO PUSH WATER FROM THE INTERIOR THEREOF DURING REVERSEOPERATION OF THE UNIT.